Help!! Pressure Relief Valve Dripping!!

I'm a DIYer that recently soldered a busted water pipe in my crawl space so I felt confident I could replace a dripping stop and waste valve in my heating system. After replacing the stop and waste valve with the newer ball valve I noticed my thermostat took a long time to heat up the house and there was a constant gushing sound in the pipes. I figured I needed to do some bleeding at the valves, but after an hour, I still kept hearing the gushing sound, but the heat was on so I thought it was ok...Well after I came home today I found water gushing out of the pressure relief valve in back of boiler!! I turned off the power, I tuned off the water coming into the system as well as the valves on the supply and return pipes into the boiler, but the relief valve is still dripping!!!

Was changing the stop waste valve to the ball valve the reason for this? Or was it improper bleeding? Lastly, how can I correct this?

I was reading some other post about the expansion tank, but mine does NOT have a shut-off valve between the tank and the boiler. I do have that air relief thing in between the expansion tank and boiler.

Boiler is a Peerless WBV-03-WPC
Expansion Tank is a Watts Regulator ET-30

Post pictures of the piping surrounding the boiler and the valve you replaced. Air issues would not cause the relief valve to drip. What pressure and temperature is the boiler gauge indicating while this is happening?

Did you use a full port ball valve? Where exactly is the sound coming from?

I'm at work right now..will post some pics when i get in today..Yes, I did use a full port ball valve with drain. Did that cause the expansion tank to go bad? Or was it a case of a novice trying to bleed air out of the system?

Not clear what that valve was doing in your system, but if it was dripping before, and now doesn't, it could have been masking an overpressure situation. IF you have an autofill valve on the boiler, it may have failed, and that is raising the pressure in the boiler loop over the typical 30# or so when the pressure relief valve on the boiler will open.

As said, need more info to help figure out what's going on. If you don't have an autofill valve, but just left the supply valve open during top off after bleeding, there's your problem.